diff options
| -rw-r--r-- | compiler/rustc_hir_typeck/src/coercion.rs | 99 | ||||
| -rw-r--r-- | tests/ui/for-loop-while/break-while-condition.stderr | 2 | ||||
| -rw-r--r-- | tests/ui/typeck/issue-100285.rs | 8 | ||||
| -rw-r--r-- | tests/ui/typeck/issue-100285.stderr | 31 | ||||
| -rw-r--r-- | tests/ui/typeck/issue-98982.rs | 8 | ||||
| -rw-r--r-- | tests/ui/typeck/issue-98982.stderr | 16 |
6 files changed, 134 insertions, 30 deletions
diff --git a/compiler/rustc_hir_typeck/src/coercion.rs b/compiler/rustc_hir_typeck/src/coercion.rs index f39d795f0ed..7f56b3850dd 100644 --- a/compiler/rustc_hir_typeck/src/coercion.rs +++ b/compiler/rustc_hir_typeck/src/coercion.rs @@ -36,7 +36,9 @@ //! ``` use crate::FnCtxt; -use rustc_errors::{struct_span_err, Diagnostic, DiagnosticBuilder, ErrorGuaranteed, MultiSpan}; +use rustc_errors::{ + struct_span_err, Applicability, Diagnostic, DiagnosticBuilder, ErrorGuaranteed, MultiSpan, +}; use rustc_hir as hir; use rustc_hir::def_id::DefId; use rustc_hir::intravisit::{self, Visitor}; @@ -53,8 +55,7 @@ use rustc_middle::ty::adjustment::{ use rustc_middle::ty::error::TypeError; use rustc_middle::ty::relate::RelateResult; use rustc_middle::ty::visit::TypeVisitableExt; -use rustc_middle::ty::GenericArgsRef; -use rustc_middle::ty::{self, Ty, TypeAndMut}; +use rustc_middle::ty::{self, GenericArgsRef, Ty, TyCtxt, TypeAndMut}; use rustc_session::parse::feature_err; use rustc_span::symbol::sym; use rustc_span::{self, DesugaringKind}; @@ -1639,12 +1640,15 @@ impl<'tcx, 'exprs, E: AsCoercionSite> CoerceMany<'tcx, 'exprs, E> { None, Some(coercion_error), ); - } - - if visitor.ret_exprs.len() > 0 - && let Some(expr) = expression - { - self.note_unreachable_loop_return(&mut err, expr, &visitor.ret_exprs); + if visitor.ret_exprs.len() > 0 { + self.note_unreachable_loop_return( + &mut err, + fcx.tcx, + &expr, + &visitor.ret_exprs, + expected, + ); + } } let reported = err.emit_unless(unsized_return); @@ -1657,8 +1661,10 @@ impl<'tcx, 'exprs, E: AsCoercionSite> CoerceMany<'tcx, 'exprs, E> { fn note_unreachable_loop_return( &self, err: &mut Diagnostic, + tcx: TyCtxt<'tcx>, expr: &hir::Expr<'tcx>, ret_exprs: &Vec<&'tcx hir::Expr<'tcx>>, + ty: Ty<'tcx>, ) { let hir::ExprKind::Loop(_, _, _, loop_span) = expr.kind else { return; @@ -1683,10 +1689,77 @@ impl<'tcx, 'exprs, E: AsCoercionSite> CoerceMany<'tcx, 'exprs, E> { ret_exprs.len() - MAXITER )); } - err.help( - "return a value for the case when the loop has zero elements to iterate on, or \ - consider changing the return type to account for that possibility", - ); + let hir = tcx.hir(); + let item = hir.get_parent_item(expr.hir_id); + let ret_msg = "return a value for the case when the loop has zero elements to iterate on"; + let ret_ty_msg = + "otherwise consider changing the return type to account for that possibility"; + if let Some(node) = hir.find(item.into()) + && let Some(body_id) = node.body_id() + && let Some(sig) = node.fn_sig() + && let hir::ExprKind::Block(block, _) = hir.body(body_id).value.kind + && !ty.is_never() + { + let indentation = if let None = block.expr + && let [.., last] = &block.stmts[..] + { + tcx.sess.source_map().indentation_before(last.span).unwrap_or_else(String::new) + } else if let Some(expr) = block.expr { + tcx.sess.source_map().indentation_before(expr.span).unwrap_or_else(String::new) + } else { + String::new() + }; + if let None = block.expr + && let [.., last] = &block.stmts[..] + { + err.span_suggestion_verbose( + last.span.shrink_to_hi(), + ret_msg, + format!("\n{indentation}/* `{ty}` value */"), + Applicability::MaybeIncorrect, + ); + } else if let Some(expr) = block.expr { + err.span_suggestion_verbose( + expr.span.shrink_to_hi(), + ret_msg, + format!("\n{indentation}/* `{ty}` value */"), + Applicability::MaybeIncorrect, + ); + } + let mut sugg = match sig.decl.output { + hir::FnRetTy::DefaultReturn(span) => { + vec![(span, " -> Option<()>".to_string())] + } + hir::FnRetTy::Return(ty) => { + vec![ + (ty.span.shrink_to_lo(), "Option<".to_string()), + (ty.span.shrink_to_hi(), ">".to_string()), + ] + } + }; + for ret_expr in ret_exprs { + match ret_expr.kind { + hir::ExprKind::Ret(Some(expr)) => { + sugg.push((expr.span.shrink_to_lo(), "Some(".to_string())); + sugg.push((expr.span.shrink_to_hi(), ")".to_string())); + } + hir::ExprKind::Ret(None) => { + sugg.push((ret_expr.span.shrink_to_hi(), " Some(())".to_string())); + } + _ => {} + } + } + if let None = block.expr + && let [.., last] = &block.stmts[..] + { + sugg.push((last.span.shrink_to_hi(), format!("\n{indentation}None"))); + } else if let Some(expr) = block.expr { + sugg.push((expr.span.shrink_to_hi(), format!("\n{indentation}None"))); + } + err.multipart_suggestion(ret_ty_msg, sugg, Applicability::MaybeIncorrect); + } else { + err.help(format!("{ret_msg}, {ret_ty_msg}")); + } } fn report_return_mismatched_types<'a>( diff --git a/tests/ui/for-loop-while/break-while-condition.stderr b/tests/ui/for-loop-while/break-while-condition.stderr index e79f6a75fde..48b29f44fa1 100644 --- a/tests/ui/for-loop-while/break-while-condition.stderr +++ b/tests/ui/for-loop-while/break-while-condition.stderr @@ -38,7 +38,7 @@ LL | while false { | ^^^^^^^^^^^ this might have zero elements to iterate on LL | return | ------ if the loop doesn't execute, this value would never get returned - = help: return a value for the case when the loop has zero elements to iterate on, or consider changing the return type to account for that possibility + = help: return a value for the case when the loop has zero elements to iterate on, otherwise consider changing the return type to account for that possibility error: aborting due to 3 previous errors diff --git a/tests/ui/typeck/issue-100285.rs b/tests/ui/typeck/issue-100285.rs index e206469b85f..460e0457105 100644 --- a/tests/ui/typeck/issue-100285.rs +++ b/tests/ui/typeck/issue-100285.rs @@ -1,6 +1,5 @@ -fn foo(n: i32) -> i32 { - for i in 0..0 { - //~^ ERROR: mismatched types [E0308] +fn foo(n: i32) -> i32 { //~ HELP otherwise consider changing the return type to account for that possibility + for i in 0..0 { //~ ERROR mismatched types [E0308] if n < 0 { return i; } else if n < 10 { @@ -15,8 +14,7 @@ fn foo(n: i32) -> i32 { return 5; } - } - //~| help: return a value for the case when the loop has zero elements to iterate on, or consider changing the return type to account for that possibility + } //~ HELP return a value for the case when the loop has zero elements to iterate on } fn main() {} diff --git a/tests/ui/typeck/issue-100285.stderr b/tests/ui/typeck/issue-100285.stderr index 9a1d5d964fa..9c8685a7712 100644 --- a/tests/ui/typeck/issue-100285.stderr +++ b/tests/ui/typeck/issue-100285.stderr @@ -4,9 +4,9 @@ error[E0308]: mismatched types LL | fn foo(n: i32) -> i32 { | --- expected `i32` because of return type LL | / for i in 0..0 { -LL | | LL | | if n < 0 { LL | | return i; +LL | | } else if n < 10 { ... | LL | | LL | | } @@ -17,7 +17,7 @@ note: the function expects a value to always be returned, but loops might run ze | LL | for i in 0..0 { | ^^^^^^^^^^^^^ this might have zero elements to iterate on -... +LL | if n < 0 { LL | return i; | -------- if the loop doesn't execute, this value would never get returned LL | } else if n < 10 { @@ -27,7 +27,32 @@ LL | } else if n < 20 { LL | return 2; | -------- if the loop doesn't execute, this value would never get returned = note: if the loop doesn't execute, 3 other values would never get returned - = help: return a value for the case when the loop has zero elements to iterate on, or consider changing the return type to account for that possibility +help: return a value for the case when the loop has zero elements to iterate on + | +LL ~ } +LL ~ /* `i32` value */ + | +help: otherwise consider changing the return type to account for that possibility + | +LL ~ fn foo(n: i32) -> Option<i32> { +LL | for i in 0..0 { +LL | if n < 0 { +LL ~ return Some(i); +LL | } else if n < 10 { +LL ~ return Some(1); +LL | } else if n < 20 { +LL ~ return Some(2); +LL | } else if n < 30 { +LL ~ return Some(3); +LL | } else if n < 40 { +LL ~ return Some(4); +LL | } else { +LL ~ return Some(5); +LL | } +LL | +LL ~ } +LL ~ None + | error: aborting due to 1 previous error diff --git a/tests/ui/typeck/issue-98982.rs b/tests/ui/typeck/issue-98982.rs index 2553824bbfe..f875d20fa4c 100644 --- a/tests/ui/typeck/issue-98982.rs +++ b/tests/ui/typeck/issue-98982.rs @@ -1,9 +1,7 @@ -fn foo() -> i32 { - for i in 0..0 { - //~^ ERROR: mismatched types [E0308] +fn foo() -> i32 { //~ HELP otherwise consider changing the return type to account for that possibility + for i in 0..0 { //~ ERROR mismatched types [E0308] return i; - } - //~| help: return a value for the case when the loop has zero elements to iterate on, or consider changing the return type to account for that possibility + } //~ HELP return a value for the case when the loop has zero elements to iterate on } fn main() {} diff --git a/tests/ui/typeck/issue-98982.stderr b/tests/ui/typeck/issue-98982.stderr index c854460c34c..d8d5a86b157 100644 --- a/tests/ui/typeck/issue-98982.stderr +++ b/tests/ui/typeck/issue-98982.stderr @@ -4,7 +4,6 @@ error[E0308]: mismatched types LL | fn foo() -> i32 { | --- expected `i32` because of return type LL | / for i in 0..0 { -LL | | LL | | return i; LL | | } | |_____^ expected `i32`, found `()` @@ -14,10 +13,21 @@ note: the function expects a value to always be returned, but loops might run ze | LL | for i in 0..0 { | ^^^^^^^^^^^^^ this might have zero elements to iterate on -LL | LL | return i; | -------- if the loop doesn't execute, this value would never get returned - = help: return a value for the case when the loop has zero elements to iterate on, or consider changing the return type to account for that possibility +help: return a value for the case when the loop has zero elements to iterate on + | +LL ~ } +LL ~ /* `i32` value */ + | +help: otherwise consider changing the return type to account for that possibility + | +LL ~ fn foo() -> Option<i32> { +LL | for i in 0..0 { +LL ~ return Some(i); +LL ~ } +LL ~ None + | error: aborting due to 1 previous error |